1. Field of the Invention
Example embodiments of the present invention relate to a cleaning solution and methods of fabricating semiconductor devices using the same. Other example embodiments of the present invention relate to a cleaning solution used for cleaning a silicon surface and methods of fabricating a semiconductor device using the same.
2. Description of the Related Art
The fabrication of a semiconductor device may include an ion implantation process to form an impurity diffusion layer (e.g., a well and source/drain regions) in a silicon substrate; a deposition or growth process to form conductive, or insulating, thin films on the silicon substrate and patterning the thin films to form various shaped-structures; a contact formation process to electrically connect stacked conductive structures such that circuits are formed; and other similar processes. The state of an exposed silicon surface in each of the processes may have an influence on the film quality of thin films formed during subsequent processes. The exposed silicon surface may deteriorate due to contamination from materials. The exposed silicon surface may be damaged during the fabrication processes. For example, the exposed silicon surface may be contaminated by various contaminated materials (e.g., a natural oxide layer, organic materials, metal impurities and/or particles) during fabrication processes or from handling the silicon substrate between the processes. The exposed silicon surface may be damaged during a dry etch process for patterning the thin films. The exposed silicon surface may be damaged during an ion implantation process for forming a well or source/drain regions.
A cleaning process for removing contaminates from the exposed silicon surface before an each process, or removing the damaged portion of the silicon surface, is generally performed. It may be necessary to perform the cleaning process before performing a process that is sensitive or may be influenced by the state of the silicon surface (e.g., an epitaxial process, a salicide process or a self-aligned contact (SAC) process). It may be necessary to remove the damaged portion of the exposed silicon surface before each process because the exposed silicon surface may function as a source of leakage during contact, or an increase in contact resistance with other layers and/or devices. The exposed silicon surface may also cause crystal defects in an epitaxial layer or a metal silicide layer contacting the exposed silicon surface. The defects may increase surface roughness of the crystal.
Generally, a standard cleaning method (e.g., standard clean 1 (SC1) which is a mixture solution including hydrogen peroxide (H2O2), ammonium hydroxide (NH4OH) and deionized water (DI water) or a diluted fluoric acid aqueous solution) may be used in the cleaning process of the silicon surface. The solution may be selected based upon the manner in which the silicon surface is used. Due to a lower etch selectivity for silicon with respect to a silicon oxide layer, it may be undesirable to use the SC1 or the diluted fluoric acid aqueous solution for an extended period of time. As such, the silicon surface may not be sufficiently cleaned. As semiconductor devices become more integrated and metals (e.g., tungsten) are used for gate electrodes, the gate electrodes may corrode during the cleaning process. Corrosion may deteriorate electrical characteristics the semiconductor devices.